Electric switch



March 17, 1931. BfE. GETCHELL 1,796,449

ELECTRIC SWITCH Filed Feb. 28, 1930 INVENTOR E etc [2e11,

O EY UNITED BETTE EGETCHELL, OF PLAINVILLE, CONNECTICUT, ASSIGNOR TO-THE TRUMBULL ELECTRIC MANUFACTURING COMPANY, OF PLAINVILLE, CONNECTICUT,A 0031901 A- TION F CONNECTICUT ELECTRIC SWITCH Q" Application filedFebruary 28, 1930. Serial No. 432,107.

My invention relates particularly to the circuit breaking contacts of aswitch, their construction and mode of operation.

My main object is to provide a construction which will have long lifeand which is ill) reliable under all circumstances.

Another object is to provide a construction which can be readilymanufactured, assembled and repaired.

Another object is to provide a construction which will reduce arcing tothe minimum.

The form of construction illustrated in the drawings is especiallyadapted to what are commonly known as motor starting switches. Suchswitches are sometimes opertill ated by hand and sometimesautomatically. My former Patents No. 1,714,085 and No. 1,714,086 showand describe complete con structions utilizing contact mechanismsembodying one form of invention. T have shown herein the improvementsembodied in a switch of that character, but it should be understood thatthe invention is only limited to the scope of the claims hereinafter setforth.

Tn its preferred form the mechanism comprises an insulating base havingpairs of spaced stationary switch contacts, each pair of contacts havinga bridging switch member movable toward and way from the stationarycontacts and preferably at an angle other than a right angle so as toproduce the efiect of a sliding or wiping contact.

This movable switch member is carried by an insulating bar which isguided in the direction desired. The movable contact mem ber is made upof two main parts or blocks which are resiliently connected anddetachably secured to the insulating carrier. The movable contact memberis also provided with a detachable abutment part which permits thecontacting portion to move relatively and thus enables it to adjustitself to the stationary contacts. Both the switch member and theabutment member are detachably held in place on astud by means of aspring and a cap both of which are readily applied to the stud orremoved as-occasion may require.

Fig. 1 is a front view of a fragment of the switch with contactsembodying the improvements of my invention.

Fig. 2 is a vertical sectional view of the same showing one of the setsof contacts in open circuit position.

Fig. 3 is a perspective view of the movable contact member and itsabutment plate.

Fig. 4C is an exploded perspective View of the parts of the movableswitch contact member and its supporting stud.

Fig. 5 is a fragmentary vertical sectional view showing the parts of theswitch in the closed circuit position.

Fig. 6 is a detail edge view of a modification of contacts.

In the usual type of switch there is an insulating base 7 carrying thevarious con ducting parts. In the particular form shown the switch isintended for a three-wire system and consequently has three switchunits. lit will be. only necessary to describe one. Each unit has twospaced stationary upper and lower contact members 8 and 9 suitablysecured to the insulating base and preferably in the channel 10. Theinsulating carrier 11 is mounted between the adjacent ends of thecontacts 8 and 9 and is movable toward and away from the base. Thiscarrier preferably has projections which are guided in side plates 13 atthe angle desired. The base is preferably provided with a recess 14 toaccommodate the carrier 11. The contact carrier is operated in thisinstance through the medium of a rocker 15 and a link 16., power beingapplied in any suitable manner to open or to close the circuits.

The carrier has a projecting stud 17 on which is supported the variousparts of the movable switch member. The movable contact consists of twoblocks or plates 18 connected by one or more layers of flexible metalstrip 19 at the back so as to permit considerable freedom of movement ofthe two plates 18 with respect to each other. The plates 18 are providedwith slots 20 to guide them on the stud 17 and the strips 19 areprovided with a passage 21 thru which the stud extends. Rivets or pins22 are secured to opposite ends of the movable switch contacts andextend through openings in the abut ment plate 23. The latter is alsopreferably provided with a passage 24 accommodating the stud 17.

The opposite ends of the abutment 23 are provided with pairs ofprojections 25 on which the contact plates 18 are adapted to tilt fromside to side so that each block or plate 18 may adjust itself to itscorrelated stationary contact and independently of the other block.lVasher 26 may be interposed at the back of the plate 18. The other endsof the pins 22 may be upset at 27 to hold the abutment plate 28 looselyin place with respect to the contact plates 1818.

The switch contacts 8 and 9 are preferably provided with raised portions28 which are curved so as to provide convex bearing surfaces for thecontact plates 18. This shape of contact has been found to affordespecial resistance to arcing. The contraction of the are by the convexsurfaces of the contacts automatically snuifs out the are so that evenunder quite severe-conditions it has practically no destructive orharmful effect.

The plates 18 and 23 are provided with a resilient abutment in the formof a spring 29 which fits over the end of stud 17 and presses againstthe central part of the abutment plate 23. This spring is held in placeby a cup-like washer member 30 having a slot 31 to receive and engage aT-shaped head 32 of the stud 17. This cup 30 also has two recesses 33adapted to receive the ends of the head 32 when the cup is rotated apartial turn and in which position the cup is retained by the pressureof the spring 29. By this means the parts of the movable contact memberare secured in assembled relation and may be very readily removedwithout the use of any tools and may be replaced in the reverse manner.

When the switch is closed the movable contact member is drawn toward thestationary contacts until they engage the same. The continued closingmovement causes the movable member to slide along on the convex contactsurfaces of the stationary contacts until the final closed circuitposition of the switch is reached, in which position the movable contactmember is held in any suitable manner against the pressure of the spring29. When the switch is released the spring 29 pulls carrier 11 outwarduntil it engages contact 18, and as this .outward movement is continuedeither by spring or gravity the contact 18 moves away from contacts 8and 9 and the circuit is opened.

The invention as herein set forth contemplates simultaneous double-breakaction contacts which provides a perfect contact of an extremely highinterrupting capacity. The contacts are self-alining and self-cleaning.

- The movable contacts are readily removable without the use of anytools and the stationary contacts may also be readily removed mamas fromthe front of the base by releasing one screw for each contact.

When the switch is released the spring 29 pulls the carrier outwardlyuntil it engages the contacts 18-18 and, as the outward moveiscontinued, either by spring or gravity, the contacts 1818 move away fromthe contacts 89 and the circuit is opened.

Due to the combination of the angular movement and the specialself-adjusting contact construction the contact closing movementproduces a sliding or wiping action under pressure so as to keep thecontact surfaces perfectly clean and free from oxidization.

This particular form of contacts and the method of operating the samehave been found to reduce the arc to something like 1/20 of thatproduced by the usual singlebreak switch.

hen the parts are accurately constructed the movable contact member andthe abutment plate are both directly guided on the stud 17. The pins orstuds 22, however, also serve as guides to hold the movable contactmembers and the abutment plate in alignment so that if either themovable contact or the abutment is properly guided on the ingspecifications describe the movable con-- tacts as being flat and thestationary contacts as being provided with arcuate contacting points ortips, it is obvious that if so desired, this arrangement may be reversedso that the movable contacts 18 are arcuate and the stationary contacts8 are flat as shown in Fig. 6, or, in some instances, it may bedesirable to combine one flat and one arcuate movable contact with oneflat and one arcuate stationary contact and it is further obvious thatthese various arrangements may be provided without departing from thespirit of the invention.

This application is a continuation in part of my former application242,560, filed December 27, 1927.

I claim:

1. A double break switch including an insulating base, a pair ofspaced-apart contacts having convex surfaces, a movable switch membercomprising an insulating carrier mounted to move between the stationarycontacts, a pair of flexibly connected contact plates, an abutment platecarrying a tilting support for the contact plates, a stud pro jectingfrom the carrier to said contact plates and abutment plate, a springmounted on said stud and a detachable cap for securing said spring onsaid stud.

2. A double break switch including two stationary contacts having convexcontact .ary contacts, a carrier between them having a projecting guidestud, two contact plates each having a slot to receive an edge of saidstud, an independently movable abutment plate. on said stud coactingwith said contact plates anda spring coacting with said abutment plate.I

4. Ina double break switch, an insulating carrier, a flat studprojecting therefrom, a switch member" movable on said stud, said studhaving a T-shaped head, a springcon said stud and a cup-like washer fordetachably securing'said switch member on said stud,said washer having aslot for receiving tionary contacts and a pair of connected vmovablecontacts, one contact of each pair,

the head of said stud and two recesses to receive the edges of the headwhen the washer is rotated. v

5. In a double breakswitch, a pair of stabeing convex at the contactingpoint, and

an abutment plate having projecting points engaging the backsof themovable contacts to permit tilting.

6. A double break switch including stationary contacts, movable contactsadapted to backing memberbeing provided with pointed projections forengaging the central portion of said connector to permit of theindependent tilting movement of S'lld connector and of said contactblocks.

BENJAMIN E. GETGHELL.

coact therewith, a carrier bar between the stationary contacts, a studprojecting from the carrier bar, said movable contacts having slots forguiding them on said stud a flexible conductor connecting the movablecontacts, pins riveted to the movable contacts, an abutment plate.guided on said pins and a spring mountedon said stud and coacting withsaid abutment plate.

7. In a double break switch, a pair of stationary contacts, movablecontacts coacting therewith, a stud for guiding the movable contacts,a'flexible conductor connecting the movable contacts, a pin extendingthrough each movable contact and having a shoulder, a washer on each pininterposed between its shoulder and'the adjacent por- An electric switchconstruction ining projections extending across its contact-making end,a pair of movable contact,

blocks, a flexible connection for said blocks,

a' relatively rigid backing member for said. blocks and said connectorand spring means for maintaining said backing means in engagement withthe said connector, the said

